An Innovative Method to Produce Soft, Recyclable Fibers for Smart Textiles

National University of Singapore, Queenstown, Singapore

Drawing inspiration from how spiders spin silk to make webs, a research team from the National University of Singapore led by Assistant Professor Swee-Ching Tan (left) has developed a simple, efficient, and sustainable method to produce functional soft fibers that are suitable for smart textile electronics. His team members include NUS research fellow Dr. Songlin Zhang (center) and NUS doctoral student Ms. Mengjuan Zhou (right). (Image: National University of Singapore)

Drawing inspiration from how spiders spin silk to make webs, a team of researchers from the National University of Singapore, together with international collaborators, has developed an innovative method of producing soft fibers that possess three key properties (strong, stretchable, and electrically conductive), and at the same time can be easily reused to produce new fibers.

The fabrication process can be carried out at room temperature and pressure, and uses less solvent as well as less energy, making it an attractive option for producing functional soft fibers for various smart applications.

“Technologies for fabricating soft fibers should be simple, efficient, and sustainable to meet the high demand for smart textile electronics,” said Assistant Professor Swee-Ching Tan. “Soft fibers created using our spider-inspired method of spinning have been demonstrated to be versatile for various smart technology applications — for example, these functional fibers can be incorporated into a strain-sensing glove for gaming purposes and a smart face mask to monitor breathing status for conditions such as obstructive sleep apnea. These are just some of the many possibilities.”

Their work was published in scientific journal Nature Electronics.

The spider silk spinning process is highly efficient and can form strong and versatile fibers under room temperature and pressure. To address the current technological challenges, the team decided to emulate this natural spinning process to create 1D functional soft fibers that are strong, stretchable, and electrically conductive. They identified two unique steps in spider silk formation that they could mimic.

The researchers first identified that the protein concentration and interactions in the silk dope increase from dope synthesis to spinning. The second step identified was that the arrangement of proteins within the dope changes when triggered by external factors to help separate the liquid portion from the silk dope, leaving the solid part — the spider silk fibers. This second step is known as liquid-solid phase separation.

The team recreated the two steps and developed a new spinning process known as the phase separation-enabled ambient (PSEA) spinning approach.

The soft fibers were spun from a viscous gel solution comprised of polyacrylonitrile (PAN) and silver ions — referred to as PANSion — dissolved in dimethylformamide (DMF). This gel solution is known as the spinning dope, which forms into a strand of soft fiber through the spinning process when the gel is pulled and spun under ambient conditions.

Once the PANSion gel is pulled and exposed to air, water molecules in the air act as a trigger to cause the liquid portion of the gel to separate in the form of droplets from the solid portion of the gel — the nonsolvent vapor-induced phase separation effect. When separated from the solid fiber, the droplets of the liquid portion are removed by holding the fiber vertically or at an angle for gravity to do its work.

“Fabrication of 1D soft fibers with seamless integration of all-round functionalities is much more difficult to achieve and requires complicated fabrication or multiple post-treatment processes,” said Tan. “This innovative method fulfils an unmet need to create a simple yet efficient spinning approach to produce functional 1D soft fibers that simultaneously possess unified mechanical and electrical functionalities.”

Researchers then tested the mechanical properties, strength, and elasticity, of the PANSion gel through a series of stress tests and demonstrated that the innovation possessed excellent strength and elasticity. These tests also allowed the researchers to deduce that the formation of strong chemical networks between metal-based complexes within the gel is responsible for its mechanical properties.

Further analysis confirmed its electrical conductivity and showed that the silver ions present in the PANSion gel contributed to the electrical conductivity of the soft fibers. The team then concluded that PANSion soft fibers fulfil all the properties that would allow it to be versatile and potentially be used in a wide range of smart technology applications.

Other applications include PANSion fibers creating an interactive smart gaming glove; detecting changes in electrical signals that could be used as a form of communication like Morse code; sensing temperature changes; and creating a smart mask to monitor breathing. In addition, PANSion fibers could be recycled by dissolving in DMF, allowing it to be converted back into a gel solution for spinning new fibers.

For more information, contact Fun Yip at This email address is being protected from spambots. You need JavaScript enabled to view it. or 65161374.